Eric Schmidt, the executive chairman of Google, has criticised China in his new book, describing the country as the world's "most sophisticated and prolific hacker".

According to extracts quoted by the Wall Street Journal, Schmidt's new book, The New Digital Age, paints a picture of a dangerous superpower using "illicit competition" to see off rivals.

"The disparity between American and Chinese firms and their tactics will put both the government and the companies of the United States at a distinct disadvantage," Schmidt writes, because "the United States will not take the same path of digital corporate espionage, as its laws are much stricter (and better enforced) and because illicit competition violates the American sense of fair play. This is a difference in values as much as a legal one."

Google has clashed repeatedly with the Chinese authorities. Beijing reacted furiously to the company's claims that Chinese authorities were hacking Gmail accounts; last year Google's service was blocked as the Communist Party appointed its first new leader in a decade.